Refrigeration



16, A. R. THOMAS 38 REFRIGERATION Filed Oct. 27, 1936 8 Sheets-Sheet 1INVENTOR l. WWJ'ZMM' ATTORNEY.

y 6, 1940. A. R. THOMAS 2,207,838

' REFRIGERATION Filed Oct. 27, 1936 8 Sheets-Sheet 2 IN VENT OR.

ATTORNEY.

July 16, 1940- A. R. THOMAS REFRIGERATION Filed Oct. 27, 1956 ssheets-shee't s INVENTOR. WWVZMMJ ATTORNEY.

Filed Oct. 27, 1936 July 16, 1940.

. 8 Sheets-Sheet 4 IN VENTOR.

ATTORNEY.

y 16, 1940- I v A. R. THOMAS 2,207,838

REFRIGERATION Filed Oct. 27, 1936 8 Sheets-Sheet 5 ATTORNEY.

y 16, 1940- A. R. THOMAS 2,207,838

REFRIGERATION Filed Oct. 27, 1956 a Sheets-Sheet s 10 2 =4 3 10 o m o oJ m 163 T INVENTQR. WWM! ATTORNEY.

July 16, 1940. v THOMAS 2,207,838

REFRIGERATION Filed Oct. 27, 1936 8 Sheets-Shget 7 ll war/A 'Q INVENTOR.F ,"10, Quzfiwd a; if;

ATTORNEY.

A. R. THOMAS REFRIGERATION Filed Oct. 27. 1936 July 16, 1940.

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PatentedJuly 1 6 1940 UNITED STATES PATENT OFFICE 2,201,838 nnrmcnaanonAlbert R. Thomas. Evansville, Ind; assignor to Servel, Inc., New York,N. Y. a corporation of Delaware Application October 2'1, 1936, SerialNo. 107,852

31 Claims.

use of evaporation of refrigerant in the presence of inert gas.

It is an object of the invention to provide an improved refrigerationsystem of this type having greater capacity and efficiency. I accomplishthis in a manner which will appear as I describe and explain anembodiment of the invention in a refrigeration system which is generallylike that described in U. S. Patent 1,609,334 granted Dec. 7, 1926, tovon Platen and Munters', and'as illustrated by the accompanyingdrawings, forming part of this specification, of which:

Fig. 1 is a vertical sectional view of an evaporator embodying theinvention;

Fig. 2 is a more or less diagrammatic view with parts in verticalsection illustrating a refrigeration system embodying the inventionincluding the evaporator shown in Fig. 1;

Fig. 3 is a detail sectional view on line 3-3 in Fig. 2;

Fig. 4 is an enlarged view of a portion of the apparatus shown in Fig.2;

Fig. 5 is a view like that of Fig. 2 illustrating a modification;

Fig. 6 is a front view with parts broken away of a refrigerationapparatus unit involving the parts and system illustrated in Fig. 2.

Fig. '7 is a rear view'of the apparatus unit shown in Fig. 6;

, Fig. 8 is a sectional view on line 3-3 in Figs.

6 and If Fig. 9 is a. sectional view on line 9-4 in Figs. 6 and '7;

Fig. 10 is a sectional view on line 10-10 in Fig. 9, so that this figureis substantially a top view of the unit; and

' and absorber.

Fig. 11 is a chart showing the effect of variation in the slope of thepiping in the evaporator In the system described in said patent grantedto von Platen and Munters, refrigerant, such as ammonia, is expelledfrom solution in an-absorption liquid, condensed, and conducted to a vessel, called an evaporator; which is in heat exchange relation with abody to be cooled. 'In thev evaporator, the liquid refrigerantevaporates in the presence of an inert gas, such as hydrogen, whichflows through the evaporator. The evaporation of the liquid refrigerantproducesrefrigeration, the heat of evaporation being transferred to therefrigerant from the body to be cooled which is in heat exchangerelation with the evaporator.

The amount of refrigeration produced depends upon the rate of heattransfer from the body to be cooled to the liquid refrigerant and therate of evaporation of the refrigerant. The refrigeration temperaturedepends upon the par-v tial pressure of the refrigerant vapor in theevaporator which in turn depends upon the. rate of removal of therefrigerant vapor from the presence of the refrigerant liquid. It willnow be understood that both the relationship of the re- 10 frigerant andthe inert gas, and the heat transfer relationship between therefrigerant liquid and the body to be cooled are important. It isdesirable that the relationship between the body to be cooled and theliquid refrigerant afford the 15 greatest rate of heat transfer and.that the relationship between the refrigerant and the inert gas affordthe desired rate of evaporation.

Referring to Fig.1, there is shown an evaporator l2 comprising agenerally upright cylindrical casing 31 inside of which there is acylinder 38 concentric with the casing 31. The upper end of the innercylinder 38 has a reduced portion or neck 39 which opens within theupper end of the outer casing 31. The inner cylinder 38 forms within theouter casing 31 an annular space 40 within which there is located a pipecoil 41 having its turns spaced equally from the outer casing 31 and theinner cylinder 38. Around the neck 39 on the upper end of the innercylinsteel mesh. This ring of capillary material extends substantiallyto the bottom on the inside of thetrough 42 and extends downward orhangs uniformly over the edge of the trough 42 and below the bottomthereof. The trough 42 and wick ring 43 are constructed and arranged sothat the outer depending edge of the latter is horizontal and locateddirectly above the top turn of the pipe coil 4|. A conduit 51 isconnected'to the lower part of the inner cylinder 33 and a conduit '53is connected to the lower end of the outer casing 31. A conduit 63extends through the outer casing 31 and has an open end above the troughWhen the evaporator I2 is connected in a suitable refrigeration system,as hereinafter described, liquid refrigerant, such. as ammonia, flowsthrough the conduit 68 into the trough 42 whence it is carried by'theannular capillary .syphon 43 and deposited on the upper turnof theevaporator coil 41 located in the annular as space 40. As the liquid isdeposited on the upper turn of the coil 4|, it spreads out and runs tothe under side of this turn. Due to the inclination of the coil turns,liquid also flows downwardly along the length of the coil. Liquid alsodrops due to its own weight from the bottom of one turn and isinterrupted by the top of the next turn. The liquid ammonia thus becomesdistributed entirely over the outer surface of the evaporator coil 4| asit descends in substantially a freefalling cylindrical sheet. Thisliquid distribution may be aided by roughening the outer surface of thecoil 4| as, for instance, by electro-deposition which creates a spongemetal surface.

I have discovered that the degree of slope or inclination of the pipingforming the coil 4| is of critical importance. Fig. 11 shows a curveobtained experimentally to determine the inclination necessary to obtainmaximum covering of the surface of the absorber and evaporator piping bythe free-falling or random dripping liquid. This is a qualitative curveobtained by measuring heat transfer to liquid dripping on the outside ofa variably inclined conduit from liquid fiowing therethrough. Themaximum surface covering occurs when the piping has an inclination ofsubstantially 4 degrees. A greater or less inclination results in lessof the surface being covered by liquid and less heat transfer. Forinstance, the surface covered when the inclination is 2 degrees issubstantially the same as that when the inclination is 8 degrees butless than the maximum when the inclination is about 4 degrees. I preferan inclination of substantially 4 degrees and not less than 2' degreesnor more than 8 degrees.

Inert gas enters the evaporator through conduit 51 and flows upwardthrough the inner cylinder 38, through the opening 39 into the upper endof the outer casing 31, and thence downwardly in the annular space 40and out through the conduit 58. The liquid which wets the outer surfaceof the coil 4| evaporates, and its vapor diffuses into the atmosphere ofhydrogen which surrounds the coil in the annular space 40. Due to thisevaporation, the liquid and gas is cooled to a temperature correspondingto the evaporation temperature at the vapor pressure of the ammonia.This is what has been referred to as refrigeration effect. Thisrefrigeration effect may be utilized for cooling by causing a suitablefluid, such as brine, to flow through the evaporator coil 4|. We mayrefer to the brine flowing in the coil 4| as the body to be cooled.

The cold refrigerant liquid and the body to be cooled, also a liquid,are in direct thermal conductive relation throughout the entire area ofthe wall of the evaporator coil 4|, the refrigerant liquid covering theentire outside of the coil and the liquid to be cooled contacting theentire inner surface of the coil. In this manner we have heat transferfrom liquid to liquid through a uniformly short metallic path throughoutthe extent of the evaporator.

In an evaporator constructed in accordance with my invention, as justdescribed, thesurface wetted by liquid refrigerant is completelysurrounded by inert gas. The turns of the evaporator coil 4| are equallyspaced from each other and equally spaced from the walls formed by theinner cylinder 38 and the outer casing 31. The smaller the spacingbetween the coil turns, the greater the evaporation and heat transfersur face for a given size evaporator. This spacing, however, should notbe so small that liquid runthe tubes II.

ning downwardly over the coil bridges the spaces between the coil turns.The spacing should be such that during operation liquid drops clear fromone turn and on to the next. Likewise, the spacing of the outer surfaceof the coil 40 from the inner surfaces of the cylinder 38 and casing 31should be as small as possible without incurring bridging of liquidbetween the coil and the walls. The reason for this is that bridging ofliquid creates localized fiow of the descending liquid, interfering withthe desired cascading thereof which completely covers the outer, surfaceof the coil. I have found that a distance of less than between coilturns and between the coil and evaporator walls is liable to incurbridging of liquid. I therefore prefer a spacing between coil turns andbetween the coil and the inner surfaces of the annular space 40 of notless than A; inch but as near this dimension as practicable, that is, onthe order of three sixteenths of an inch.

Referring to Fig. 2 of the drawings, there is illustrated more or lessdiagrammatically a refrigeration system including a generator III, acondenser II, the above described evaporator I2, and-an absorber I3. Thegenerator I0 and the absorber I3 are connected for circulation of liquidtherebetween by members including a liquid heat exchanger I4. Theevaporator I 2 and the absorber I3 are interconnected for circulation ofgas therebetween by members including a gas heat exchanger I5. Thegenerator Ill is connected to the condenser I I' for flow of vapor fromthe generator to the condenser, and the condenser II is connected to theevaporator I2 for flow of liquid from the condenser to the evaporator bymembers hereinafter described.

The generator I0 comprises a casing I6 in the form of an uprightcylinder. A plurality of flues or fire tubes I1 extend verticallythrough the easing I6. At the bottom of the casing I6 is a heating orcombustion chamber I8, and the lower ends of the fire tubes I! open inthe'upper part of this chamber. A flue, not shown in this figure, may beprovided for conducting flue gases from the upper ends of the tubes IT.A suitable heater such as a gas burner I9 is located beneath thecombustion chamber I8 so that the burner flame is projected into thischamber and thence into The tubes I! provide 'a desired surface fortransferring heat to liquid surrounding these tubes in the casing I6.

A pipe coil 20 is located in the chamber I8 above the burner I9 so as tobe heated directly by the burner flame. The lower end of the coil 20 isconnected to the lower end of an upright conduit 2|. nected to the lowerpart of the generator casing I6. The upper end of the coil 20 isconnected by a rising conduit 22 to the upper part of a gas and liquidseparating vessel 23. The upper end of the generator casing I8 is alsoconnected to the upper part of the vessel 23 by a conduit 24. Theinternal diameter of the conduit forming the coil 20 and the risingconduit .22 is advantageously su'fiiciently small that gas and liquidcannot pass each other therein so that gas formed by vaporization ofliquid in the coil 20 will be trapped as bubbles in liquid, therebyadding a piston effect to the resulting decrease in weight of a fluidcolumn in the coil 20 and conduit 22 compared to an equal column ofliquid to effect upward flow of liquid in the coil 20 and conduit 22into the vessel 23. Although only one coil 20 and rising conduit 22 areillustrated in this figure, it will be un- The upper end of the conduit2| is conr to derstood that a plurality of such coils and risingconduits may be provided.

The upper part of the generator casing I6 is connected to the lower endof a slightly tilted but generally horizontal conduit 25, which will beherein referred to as an analyzer. The analyzer 25 is provided with aplurality of baflies or partitions 26 each provided with an opening 21in the upper part thereof and an opening 28 in the lower part, thereof.These openings may best be seen in Fig. 3. The upper opening 21 is inthe form of a horizontal slot having serrations in the upper edgethereof. The lower opening .28 may be a circular hole. The upper end ofthe analyzer 25 is connected to the lower part of a vessel 29 which maybe considered'as part of the analyzer.

The upper part of the analyzer vessel 29 is connected by means of aconduit 36 to the lower end of a rectifier 3|. The rectifier 3|comprises an upright tube 32 surrounded by'a jacket 33. The

lower end of the tube 32 projects through the bottom of the jacket 33,and the upper end of the tube 32 is open in. the-upper part of thejacket 33. The interior of the tube 32 may be provided with suitablefins or baflles 34. The upper end of the rectifier jacket 33 isconnected to the upper end of the condenser The lower end of thecondenser II is connected by means of a conduit 35 to the righthand legof a U-shaped conduit 36. The right hand leg of the conduit 36 extendsappreciably above. the lower end of the condenser II, and the, left-handleg of the conduit 36 is very short and connected to the rectiflerjacket 33 at a point appreciably below the lower end of the condenserII.

The evaporator |2 has been described in connection with Fig. 1 and theparts are indicated by the same reference numerals as in Fig. 1.

The absorber I3 is constructed somewhat similarly to the evaporator l2.It comprises an upright cylindrical casing 44 and an inner cylinder 45concentric therewith and forming therebetween an annular space 46.Within the annular space 46 is located a pipe coil 41 with its turnsspaced equidistant from the outer casing 44 and the inner cylinder 45.The-upper and lower ends of the inner cylinder 45 are closed, exceptthat the lower end is provided with an opening 48 and the upper end isconnected by means of a conduit 49 to the upper end of the right handleg of the U-shaped conduit 36 previously described. On the upper end ofthe inner cylinder 45 is located an annular trough 56. Over the outerrim of the trough59 is located a ring of capillary material 5| ofinverted U- shape, the inner edge extending substantially to the bottomof the tray'or trough 50, and the outer edge being horizontal anddepending uni 'formly below the bottom of the trough and locateddirectly over the upper turn of the pipe coil 41. This structure is bestshown in the enlarged detail view of Fig. 4.

The gas heat exchanger |5 comprises a generally horizontal cylindricalcasing 52 containing a plurality of horizontal tubes 53. The tubes 53connect end chambers 54 and 55 formed by partitions in the casing 52.The end chambers 54 and 55 connected by the tubes 53 form one passage ofthe gas heat exchanger, andthe space around the tubes 53 forms the otherpassage 01' the heat exchanger. The upper part of-the absorber I3 isconnected by a conduit 56 to one end chamber 54 of the gas heatexchanger, and

the other end chamber 55 is connected by a. conof the evaporator l2. Thelower part or the outer casing 31 of the evaporator I2 is connected by aconduit 56 to one end of the space around the tubes 53, and the otherend of this space is connected by a conduit 59 to the lower part of theabsorber l3.

Referring now to the connections for circulation of liquid between thegenerator In and the absorber I3, the lower part of the gas and liquidseparating vessel 23 is connected to the upper part of tneabsorber I3 bya conduit 69, the inner passage of the liquid heat exchanger l4, and aconduit 6|. The upper end of the conduit 6| depends above the absorbertray 50. The lower part of the absorber I3 is connected to the analyzervessel 29 by a conduit 62, the outer pas-- sage of the liquid heatexchanger l4, and a conduit 63.

Adjacent the top of the evaporator I2 is a looped conduit 64, which maybe referred to as a high temperature evaporator or precooler. The upperpart of the ends of this evaporative precooler are connected by conduitsand 66 respectively to the chamber in the gas heat exchanger |5 whichsurrounds the tubes 53. A conduit 61 is connected from the bottom of theU-shaped tube 36 to one end of the conduit 64, and one end of a conduit66 is connected to the other end of the conduit 64. The other end ofconduit 69 extends into the evaporator l2 and depends above theevaporator trough 42.

The upper end of the evaporator coil 4| is connected to the upper end ofa cooling coil 69 in a chamber to be cooled 10. The lower end of thecooling coil 69 is connected to a suitable pump II or other liquiddisplacing means which in turn is connected to. the lower end of theevaporator coil 4|.

The upper end of the absorber coil 41 is con-. nected by a conduit 12 toa condenser cooling coil .13. The other end of the condenser coolingcoil 13 is connected to a conduit 14 which extends in thermal contactwith a,portion 15 of conduit 30, which will herein be referred to as afirst rectifier or high temperature rectifier. The lower end of theabsorber coil 4'! is adapted to, be connected to a source of coolingwater by means of and a certain condenser temperature which may be afairly high cooling water temperature, or

room temperature'should the condenser "be aircooled. The liquid assumesthe lowest possiblev level in the system, and the space above the liquidis filled with gas. When the burner I9 is lighted, heat from the burneris transmitted directly to the coil 26, and by means of the fire tubesIT to the liquid in the generator casing 6. Heating of liquid in thecoil 26, causes expulsion of ammonia vapor out of solution. The expelledvapor creates in the coil 20 and the rising conduit 22 a fluid columnlighter than an equivalent column of liquid only. so that thecombination vapor and liquid column .rises in conduit22 into the gas andliquid separating vessel 23. From the vessel 23; the gas flows inconduit 24 to the 24 upper part of the generator casing l6. Heating ofliquid in the generator casing It also causes expulsion of ammonia vaporout of solution when the boiling point of the solution is reached. Thisvapor rises into the upper part of the generator casing l6. The vaporwhich accumulates in, the upper part of the generator casing l6 escapestherefrom by bubbling through liquid in the analyzer conduit 25 and theanalyzer vessel 29. The baffle plates 26 in the analyzer conduit 25prevent the vapor from merely flowing along under the top of the conduit25, and cause the vapor to pass downwardly and through the slots 21 inthe discs 26. The serrations in the upper edge of the slots 21 break upthe vapor flow so as to create a more extensive contact of the vaporwith the liquid as they flow in countercurrent relationship through theanalyzer conduit 25. Liquid from the separation vessel 23 flows throughconduit 60, the inner passage of the liquid heat exchanger Hi, andconduit 6| into the upper part of the absorber l3. During operation ofthe system, ammonia vapor is expelled from solution in the generatorcasing at a first temperature, and more ammonia vapor is expelled fromsolution in the coil 20 at a higher temperature, so that liquid whichenters the ab sorber l3, as just described may be referred to as weakabsorption liquid, this phraseology having reference to the relativelylow concentration of ammonia; In the absorber l3, the weak absorptionliquid becomes enriched by absorption of ammonia vapor, as hereinafterdescribed, and the enriched absorption liquid flows from the lower partof the absorber through conduit 62, the outer passage of the liquid heatexchanger l4, and conduit 63 into the analyzer vessel 29 and theanalyzer conduit 25 back to the generator ID. The lower openings 28 inthe analyzer baflles 26 permit the flow of liquid in the analyzer 25countercurrent to the previously described flow of vapor therethrough.The ammonia vaporpasses out of contact with liquid in the analyzervessel 29 at a place where the liquid has a high concentration ofammonia. The purpose of this is to decrease the amount of water vaporleaving the generator.

Vapor flows from the upper part of the analyzer vessel 29 throughconduit 30, the high temperature rectifier I5, and the liquid cooledrectifier 3| into the upper end of the condenser ll. Water vaporcondensed in the rectifiers flows back through conduit 30 to the liquidcircuit. In the condenser ll. ammonia vapor, substantially at the totalpressure in the system, is condensed to liquid by heat transfer to waterflowing through the condenser cooling coil l3. The liquid ammonia flowsfrom the lower end of the condenser ll through conduit 35 into the U-shaped conduit 36 and the rectifier jacket 33. It will now be understoodthat the liquid in the rectifier jacket 33 causes cooling of therectifier 3|. Cooling water from the condenser cooling coil 13 flowsthrough conduit 14 in heat exchange P relation with the conduit 30-at I5and causes cooling of this higher temperature rectifier.

Liquid ammonia flows from the lower part of the U-shaped conduit 36through conduit 61 into one end of the evaporative precooler formed bythe looped tube 64. The liquid flows along the lower part of the tube 64to the other end thereof whence it flows through conduit 68 into theupper part of the evaporator.

During operation of the system, the inert hydrogen gas is substantiallyconfined to the circuit including the evaporator l2 and the absorber 63which are interconnected as previously described by the gas heatexchanger l5.

In the evaporator l2 the ammonia evaporates in the presence of hydrogen,as set forth in connection with Fig. l, and the cooling brine or otherheat conducting liquid flows through the evaporator coil 4| and thencethrough the cooling coil 69 in heat transfer relation with air in theenclosure 10. Liquid may be circulated between the cooling coil 69 andthe evaporator coil 4| by means of the pump 1|. In the evaporator coil4!, the brine is cooled by'heat' transfer to the liquid ammonia on theouter surface of this coil. In the cooling coil 69, the brine is warmedby heat transfer thereto from air in the enclosure 10. The pump H isconnected and arranged to cause circulation of the brine so that itflows upweirdly through the evaporator coil 4|. The reason for this willbe hereinafter explained.

In order that evaporation of liquid ammonia may continue in theevaporator l2 at the desired temperature or temperatures, it isnecessary to remove ammonia vapor from the atmosphere around theevaporator coil 4| so. that the partial pressure of ammonia will bemaintained at the desired value. To this end. the mixture of gas andvapor, herein referred to as rich gas, is removed from the evaporatorand replaced by what is herein termed weak gas, that is, gas containinga relatively small quantity of ammonia vapor.

The strong gas from the evaporator I2 is conducted through conduit 58,the gas heat exchanger l5 and conduit 59 into the lower part of theabsorber I3. Weak absorption liquid emerging from the upper end ofconduit 6| in the absorber I3 is deposited in the absorber distributingtray or trough 50 from which it is transferred by the annular capillarysyphon 5| onto the upper turn of the absorber coil 41 in the annularspace 46. The liquid flows downwardly over the absorber coil 41 in thesame manner as the liquid ammonia fiows downwardly over the evaporatorcoil 4|, as previously described. Ammonia vapor diffuses out of the atmosphere in the annular chamber 46 of the absorber and enters intosolution at the surface of the liquid'wetting the absorber coil 41. Thisabsorption of ammonia is accompanied by liberation of heat which istransferred from the absorption liquid to cooling water which flows inthe absorber coil 41. Weak gas from the absorber is conducted throughconduit 56. the gas heat exchanger l5, conduit 51, and the innercylinder 38 of the evaporator l 2 to the upper part of the evaporator.

The manner in which thegas circulation ocours is as follows: Thespecific density of ammonia vapor is greater than that of hydrogen,

so that the column of gas formed by diffusion of ammonia vapor into theatmosphere. of the evaporator I2 is heavier than the column of gasformed when ammonia vapor is removed from the atmosphere in the absorberl3. The resulting unbalance between these two columns of gas createscirculation thereof, upward in the absorber l3, and downward in theevaporator l2. In the gas heat exchanger l5, heat is transferred fromthe weak gas flowing in the tubes 53 to the strong gas flowing in thechamber around, these tubes.

Referring now to the looped tube 64, the ends of this tube are connectedby conduits and 66 respectively to the chamber around the tubes 53 ofthe gas heat exchanger l5. There is, therecircuit.

' orator.

por'in the atmosphere in this tube, the tendency to equalize results inevaporation of liquid and cooling thereof before entrance into theevaporator l2. The formation of vapor in the evaporative precooler 64results in flow of gas in the path formed by conduit 55, the tube 64-,and conduit 58 due to the difference in weights of the columns of gas inthis path.

Referring now to the vessel 45 within the absorber l3, the upper end ofthis vessel is connected by conduit 49 to the. upper end of the righthand leg of the U-shaped conduit 36, and the lower end of the vessel 45communicates with the interior of the absorber through the opening '48.During normal operation of the system, the

vessel 45 contains gas having a concentration of ammonia vaporsubstantially like that in the lower part of the absorber. The conduit49 normally provides a passage for non-condensible gas which may issuefrom the lower end of the condenser through conduit 55, the right handleg of the trap 36, and conduit 49 back to the gas If the temperature ofthe cooling water in the condenser cooling coil 13 should be abnormallyhigh so that the condenser temperature is too high for condensation ofammonia at the existing pressure in the system, uncondensed ammoniavapor will flow through conduit 48 into the vessel 45, displacing gasfrom this vessel through the opening 48 into the absorber l8 which is inthe active gas circuit. In this manner, a rise in pressure in the systemtakes place so that condensation of ammonia may continue at thehighertemperature. The vessel 45 is herein referred to as a pressure vessel.During periods when the cooling water temperature is high, the pressurevessel 45 acts as a continuation of the condenser, and ammonia vaporcondensed herein returns to the liquid circuit through the opening 48 inthe bottom.

Let us return now to the structures of the evaporator l2 and theabsorber l3 in Figs. 1 and '2, these structures being essentially thesame as far as gas and. liquid contact is concerned. Re-

ferring more particularly to the evaporator 12,

we have previously described the location of the helical pipe coil 4| asbeing in an annular space 40 between the inner and outer walls of theevap- This of course istrue, but this location of the coil 4| furtherdivides the annular space 40 into two annular spaces, one on the insideof the coil 4| and the other on the outside of the coil 4|. The liquidrefrigerant, ammonia, is dripping or cascading downward over the coil 4|so that the inert gas, hydrogen, flows in two annular paths with respectto the liquid ammonia. The ammonia evaporates atthe surface of the.liquid on the coil 4| and the resulting ammonia ture and pressure ofthe ammonia. Howeven, -this state of equilibrium is not reached duringoperation because, due to circulation of gas as previously described,the rich gas is continually replaced in the evaporator by weak gas.Whether the gas is flowing or standing still, there is a maximumdistance through which ammonia yapor has to move from where it is formedat the liquid surface in tending to establish equilibrium. 5

Since the coil 4| is located centrally of the annular-space 40, themaximum diffusion distance from the .coil into the space 40 is less thanthe Width of the space 40. Since all the diffusion distances, that is,the distances in directions nor- 10 mal to the liquid surface, are notall exactly the same, we may better refer to the mean diffusiondistance.- It has been found that the capacity or quantity of liquidevaporated per unit of time is increased upon decrease in the meandiffusion 15 distance. This is the reason that, ,as previously setforth, the spacing between the coil 4| and the walls of the evaporatoris made as small as possible. In the present embodiment, bridging ofliquid is a limiting factor of this spacing. I ,0

wish to point out, however, that I may replace the coil 4| by a cylinderof, for instance, capillary material, and obtain a very small gas spacenormal to the liquid surface. Also, I may distribute the liquid overboth the inner and outer wall 25 surfaces of the space 40 rather thanover a member in the center of the space 40 and still have a diffusiondistance less than the width of the space 40. In. this case the gaswould still flow in two annular paths with respect to the 30 liquidsurface in a small evaporator, provides for better heat transfer fromthe liquid ammonia to the liquid to be cooled which flows in the coil,and effects a novel and eificient gas flow as will hereinafter appear.

The diffusion distance cannot be made zero 40 because this would meanthat there wouldbe no gas and therefore no evaporation of ammonia at atemperature lower than the condenser temperature and no refrigerationwould be produced.

Neither should the decrease in diffusion distance 45 of ammonia vapor inthe gas which leaves the evaporator l2 through conduit 58, referring toFig. 2. The density of the weak gas is determined by the averageconcentration of ammonia vapor in the gas leaving the absorber l8,through conduit 56. Throughout the evaporator and the absorber there isa gradient density'between that of the rich and weak gas. As previouslyexplained, it is the inherent force within the system due to thedifference in specific densi-- ties of the rich and weak gas columnswhich causes the gas circulation. Part of this force causes actualmovement of gas and another part of this force is expended inovercoming-resistance in the gas circuit comprising the evaporator, the

absorber, the gas heat exchanger, and the inter- 7o connecting conduitspreviously described. I have therefore provided in the evaporator andthe absorbr a path of gas flow having a very small difl'usion distancebut a large cross sectional area.

In the evaporator this is the cross sectional area 7 of the annularspace between the coil 4| and the inner wall 38 plus the cross sectionalarea of the annular space between the coil 4| and the outer wall 31. Imay make the evaporator l2 as large or as small as desired and bykeeping the same width annular space 40 the diffusion distance in thelarge evaporator will be no more than in the small evaporator althoughthe cross sectional area in the path of gas flow will be greater toaccommodate more gas in the larger evaporator.

From the above it will be understood that other things, such as liquidsurface and heat transfer, being constant, the capacity varies with therate of gas flow and inversely with the mean diffusion distance. Underconstant conditions evaporation of liquid into a moving stream of gasisproportional to the square root of the velocity. However, in therefrigeration system we have to take into consideration that gas flowingbetween the high temperature absorber and the low temperature evaporatorincurs a heat loss which is cut down only within the efficiency of theheat exchanger. Other things being constant, then, the maximumefficiency would be obtained when the gas flowing from the evaporator tothe absorber contains saturated ammonia vapor. This is not obtained onaccount of the concentration gradient of ammonia vapor from the surfaceof the liquid ammonia in the direct.on of the diffusion distance intothe gas stream. With a smaller mean diffusion distance, a desiredaverage concentration of gas leaving the evapor; or is reached in ashorter length of time, that is, a unit quantity of gas passes throughthe evaporator in a shorter length of time and the velocity of gas flowthrough the evaporator is thus increased resulting in an increase incapacity without'sacriflcing emciency.

As the gas flows through the evaporator I2, and the same thing happensin the absorber l3, it passes alternately into annular streams on eachside of the coil 4| and then in a single large annular stream betweenthe turns of the coil. The cross sectional area of each of the twoseparated streams being much less than the cross sectional area of theintermediate large stream, the resulting alternations in energy of flowproduce turbulence. This turbulence in the gas stream results inconvection of ammonia vapor from the surface of the liquid ammodia intothe gas stream. This aids the natural diffusion of ammonia and resultsin an increase of efliciency and also greater capacity because a desiredaverage concentration of ammonia in the gas is reached in a shorterlength of time. In the absorber the convection aused by turbulence abetsnatural difiusion oi .nmonia vapor out of the gas stream to the surfaceof the absorption liquid. Herein I have used the word difiusion in atechnical sense of either dispersion or concentration of one vapor'orgas in a space occupied by another gas. With respect to the evaporatorwe say that the ammonia vapor diffuses into the'hydrogen and withrespect to the absorber we say that theammonia vapor difluses out of thehydrogen.

In Fig. 5 is shown a system like that previously described in connectionwith Fig. 2 and like parts in these two figures are indicated by thesame reference numerals. Whereas in the system illustrated in Fig. 2 theabsorber l3 and the condenser II are cooled by a supply of water whichgoes-to waste, I may provide an evaporative cooling circuit or spraytower for the absorber l3 and condenser II as illustrated in Fig.

5. The condenser H is located in a housing 11 having a water tank 18 inthe lower part thereof. Air enters the casing 11 through an opening 19below the condenser II and is discharged by a fan or blower 90 above thecondenser, thus causing a flow of air over the condenser coil Water isadmitted to the tank 18 through a conduit 8| regulated by a floatcontrolled valve 82. The tank 18 is connected by a conduit 83 to thelower end of the absorber coil 41. The upper end of the absorber coil isconnected by a conduit 84 to a pump 85 which is in turn connected by aconduit 86 toa spray nozzle 81 above the condenser coil Cooling waterfrom the tank 18 flows through conduit 83 into the absorber coil 41 andis then raised by the pump 85 through conduits 84 and 86 to the spraynozzle 81 from which the water is showered onto the condenser coil Dueto the upward flow of air through the casing 11,- the water, sprayeddownwardly therein is cooled toward its wet bulb temperature. Water lostby evaporation into the air stream is replaced from conduit 8| under thecontrol of the float operated valve 82.

The upper end of the evaporator coil 4| is connected by a conduit 88 toa spray nozzle 89 in a casing 90. A water tank 9| in the lower part ofpump 93 raises water from the tank 9|; through the evaporator coil 4| tothe spray nozzle 89 which showers the water down through the casing backto the tank 9|. Air froni a room 95 to be cooled is circulated by a fanor blower 96 through a conduit 91 and a conduit 98 to the .lower part ofthe spray tower 90, and thence upwardly through the spray tower to aconduit 99 through which the air is returned to the room 95. Fresh airmay be admitted through a conduit mo. The air in passing upwardlythrough the spray tower 90 is cooled by the cold water from the nozzle89. Suitable baffle plates llll may be provided to disentrain free waterfrom the stream of air before it is returned to the room 95.

In both of the arrangements illustrated in Figs. 2 and 5, water or brineis circulated upwardly through the evaporator coil 4|. The gas flowsdownwardly-in the annular/passage 40 in which the coil 4| is located.Since the partial pressure of ammonia in the gas increases in thedirection of the gas flow, the region of lowest partial pressure and,therefore, the lowest evaporator temperature is in the upper part of theevaporator adjacent to where the weak gas enters. Thus, the waterflowing upwardly through the evaporator coil 4| is progressively cooledand leaves the evaporator substantiallyat the place of lowesttemperature, thereby utilizing the full cooling effect of theevaporator.

absorber I3 is provided with the desired annular'gas passage by locatingtherein the cylindri-,

cal pressure vessel 45, thereby effecting the desired absorber structureand at the's'ame time eliminating the requirement of additional space Ifor a pressure vessel.- The evaporator precooler y no to the evaporator212.

For instance, it may be thermostatically regulated responsivetotemperature of the evaporator I 2.

In Figs. 6 to 10 is shown a refrigeration apparatus unit embodying myinvention. The parts of this apparatus are substantially as described inconnection with the system shown diagrammatically in Fig. 2, and areconnected in the same manner. The apparatus is mounted in a rectangularframe 209 composed of angle irons. The generator 210 is locatedsubstantially centrally in the lower part of the frame. The liquid heatexchanger 214 is formed by a concentric tube coil which encircles thegenerator casing 216-. A fiue 208 is provided for conducting spent.

and have their lower ends connected to the lower end of the uprightconduit 221, the upper end of which is connected to the lower part ofthe generator casing 216. The upper ends of the coils 220 are connectedby means of rising conduits 222 to the gas and liquid separating vessel223. The

26 upper part of the vessel 223 is connected to the generator by meansof -a conduit 224, and the lower part of the vessel 23 is connected tothe liquid heat exchanger 214 by conduit 260. The analyzer'225 andanalyzer vessel 229 are like that 30 .described in connection with Fig.2. The generator 210, the liquid heatexchanger 214, the separatingvessel 223 and its connections, and the analyzer 225 are-enclosed bysuitable thermal insulating material 201, such as mineral wool which isretained in place by a light sheet metal casing 206. Any suitableheater, not shown, may be arranged directly beneath the coils 220 in theheating chamber 218.

V The evaporator 212 and the absorber 213 are 40 located at oppositeends of the frame 209, the absorber 213 being at a level above that ofthe generator 210,'and the evaporator 212 being somewhat higher than theabsorber 213. Members interconnecting the-absorber and the evaporatorinclude a gas heat exchanger 215 similar to that described in connectionwith Fig. 2. The evaporative precooler coil 264 is located directlyabove the upper end of the evaporator 212, and this precooler, theevaporator, and adjacent portion of the gas heat exchanger 215 areencased by suitable thermal insulation material 205.

I The condenser 21 I comprises a concentric tube coil located adjacentthe top of. the frame 209 -and encircling the leg of the rectifierU-tube 236 which is connected by the vent conduit 249 to the pressurevessel 245 within the absorber 213. The lower part of the U-tube 236 isconnected by the conduit 261 to the evaporative precooler 264 which inturn is connected by conduit 268 The evaporator precooler 264 isconnected to the gas heat exchanger 215 by conduits 265 and 266. Theabsorber 213, the condenser 2| 1, and the high temperature rectifier 215are cooled by water 65 which flows from conduit 216 upward through theabsorber coil 241, then through conduit 212 to the condenser coolingcoil, and thence through conduit 21.4 which extends in thermatcontactconduit 268 into the evaporator 212.

evaporator coil respectively and to which connection may be made forfiow of fluid to be .best be followed by reference to Fig. 6. Vaporexpelled from solution in the coils 220 causes upward flow of vapor andliquid in the rising conduits 222 into the separating vesse1223 in themanner previously described. Vapor flows from the vessel 223 throughconduit 224 into the upper part of the generator casing 216, from whereall the vapor bubbles through liquid in the analyzer .225 and passesinto the analyzer 'vessel 229.

From the vessel 223, liquid flows through conduit 260, the liquid heatexchanger 214 and conduit 261 into the upper part of the absorber 213.Enriched liquid fiows from the lower part of the absorber 213 throughconduit 262, the liquid heat exchanger 2,14, and conduit 263 into theanalyzer vessel 229 from where it flows to the analyzer conduit 225 intothe generator.

Vaporflows from the upper part of the analyzer vessel 229 throughconduit 230 to the liquid cooled rectifier 231. Watenvapor condensed inthe high temperature rectifier 215 and in the liquid cooled rectifier231 flows back to the liquid circuit through conduit 230. Ammonia vapor(here see Fig. 7) flows from the low temperature rectifier 231 into theupper end of the condenser coil 211. In the latter, the ammonia vapor,substantially at the total pressure in the system, is condensed to,liquid which fiows through conduit 235 into the rectifier U-tube 236.From the lower part of the U-tube 236, liquid ammonia fiows throughconduit 261, the evaporative precooler 264, and In the evaporator,theliquid flows downwardly over the evaporator coil 241, in a mannerpreviously described, and evaporates, producing a refrigerating effectto cool fluid in the coil .241. The vapor diffuses into the atmosphereof inert gas, hy-

drogen. Rich gas fiows from the evaporator 212 through conduit 256, thegas heat exchanger 215, and conduit 259 into the absorber. In thelatter, ammonia vapor diffuses out of the gas and is absorbed intoweakened solution flowing downwardly over the absorber coil 241. Theweak gas returns from the absorber to the evaporator through conduit256, gas heat exchanger 215, and conduit 251. Rich gas from the gas heatexchanger 215 flows through conduit 265, the evaporative precooler 264,and conduit 266.

Although I have described and explained my invention as embodied in aparticular type of system'in which gas circulation is automaticallyproduced by a force within the system, it will be understood that it maybe practiced in any system whichmakes use of evaporation of refrigerantin the presence of inert gas, whether gas circulation is produced by afan, blower, injector, turbine, or other gas impelling means. It. willalso be understood that there may be variations in structure as, forinstance, the use of banks of tubes or pipes instead of the helicalcoils in the evaporator and absorber, or both. My 111-.

an I

ventlon, therefore, is not limited except as indicated by the followingclaims.

What I claim is:

l. Refrigeration apparatus of the absorption type employing an inert gasincluding structure for effecting gas and liquid contact comprisingpiping having sections thereof arranged one above the other, and meansfor delivering liquid upon said piping so that the liquid descends bygravity from one section to another and over the exterior surface ofsaid piping, said piping having a slope of substantially four degrees toeffect substantially maximum wetting of the exterior surface thereof bythe descending liquid.

2. Refrigeration apparatus of the absorption type employing an inert gasincluding structure for effecting gas and liquid contact comprisingpiping having sections thereof arranged one above the other, and meansfordelivering liquid upon said piping so that the liquid descends bygravity from one section to another and over the exterior surface ofsaid piping, said piping having a slope lying in a range between andincluding two and eight degrees.

3. Absorption type refrigeration apparatus employing an inert gasincluding a generator, a condenser, an evaporator, an absorber, apressure vessel located within said absorber and communicatingtherewith, and a conduit connected from the outlet end of said condenserto said pressure -vessel.

4. Absorption refrigeration apparatus employing an inert gas including agenerator, a condenser, an evaporator, an absorber, said absorber havinginner and outer walls forming therebetween a substantially annular spacefor flow of inert gas, said inner wall enclosing a storage chamber forinert gas, a connection from said chamber into the absorber space, and aconduit connected from the outlet end of said condenser to said chamber.

5. In an absorption refrigerator, a generator, a condenser, anevaporator, an absorber, and members connecting said parts to form asystem for flow of refrigerant, absorption liquid, and inert gas, saidabsorber including a cylindrical member constituting a pressure vessel,an outer shell concentric with said vessel, means to provide a cascadeof absorption liquid midway between said vessel and said outer shell, aconnection between said vessel and a point in the system between thegenerator and the evaporator, and said vessel being connected to theabsorber space outside the same.

6. In a refrigerating apparatus of the kind in which refrigerantevaporates into inert gas, an evaporator including spaced verticalwalls, vertically spaced pipe portions between said walls equidistantlyspaced therefrom, said pipe portions being disposed for dripping ofliquid from one to another along tneir length and being spacedvertically to prevent bridging of liquid, said pipe portions being soclose to said vertical walls as to provide minimum diffusion distance,without bridging of liquid, means to cause flow of gas between saidwalls, means to supply liquid refrigerant to flow over said pipeportions, and means to circulate fluid to be cooled through said pipeportions.

'7. In a refrigeration system of the kind in which refrigerant liquidevaporates and diffuses into an inert gas, the improvement whichconsists in alternately flowing the liquid refrigerant inert gas on eachside of the free falling liquid refrigerant in direct contact therewithin paths of like characteristics and of a width on the order of threesixteenths of an inch.

8. A refrigeration system including structure forming an annular placeof evaporation, a member for conducting liquid refrigerant fluid to saidplace of evaporation, members for conducting inert gas to and from saidplace of evaporation, and a pipe coil arranged concentrically insaidannular place and constructed and arranged to form a downward pathof flow for liquid refrigerant fluid on its exterior surface andinteriorly conduct a fluid to be cooled, the width of said annular placebeing such that with said pipe coil therein, there is a minimumdiffusion distance for refrigerant in inert gas without bridging ofliquid.

9. A refrigeration system including an evaporator formed by twoconcentric upright cylindrical members providing an annular spacetherebe' tween, a pipe coil located in said annular space substantiallyequidistant from both said members, a member for conducting liquidrefrigerant fluid to the upper part of said annular space, means forconducting inert gas through the in ner upright cylindrical member andto one mid of said annular space, and means for conducting inert gasfrom the opposite end-of said annular space, said pipe coil beingconstructedand arranged to interiorly conduct fluid to be cooled, areceptacle for liquid conducted to the upper part of said annular space,and a capillary syphon for distributing liquid from said receptacle ontoan upper turn of said pipe coil.

10. In a refrigeration system of the kind in which refrigerant liquidevaporates and diffusesinto an inert gas, the improvement which consistsin dripping liquid refrigerant in a sheet-like path in free fallingcondition, obstructing the free fall of liquid in said path, flowinginert gas on each side of said sheet-like path in direct contact withthe liquid refrigerant in paths of like characteristic and of a width onthe order of three sixteenths of an inch, and transferring heat from anobject to be cooled to the obstructing medium.

11. In a refrigeration system of the kind in which refrigerant liquidevaporates and diffuses into an inert gas, the improvement whichconsists in flowing liquid refrigerant in free falling condition in asheet-like path of annular form, flowing a medium, to be cooled throughsaid path in indirect heat transfer relation with the liquid refrigerantand thereby obstructing the free fall of liquid refrigerant, and flowinginert gas in narrow unobstructed paths of like characteristics,including width and variations of width, on each side of the sheet-likepath in direct contact with the liquid refrigerant, the width of theinert gas path being such as to provide a minimum diffusion distancewithout bridging of liquid.

12. In a refrigeration system of the kind in which refrigerantliquid'evaporates and diffuses into an inert gas, the improvement whichconsists in flowing liquid refrigerant in free falling condition in asheet like path of annular form, flowing a medium to be cooled throughsaid path in indirect heat transfer relation with the liquid refrigerantand thereby obstructing the free fall of liquid refrigerant, flowinginert gas in narrow unobstructed paths downward on each side of thesheet-like path in direct contact with the liquid refrigerant, andconducting inert gas prior to contact with the liquid refrigerant inindirect heat exchange relation with the inert gas in one vent bridgingof liquid, means to cause flow of gas between said walls, means tosupply weak absorption liquid to flow over said pipe portions, and meansto circulate cooling fluid through said pipe portions.

14. An absorption refrigeration system including structure forming asubstantially annular place of absorption, a member for conductingabsorption liquid to said place of absorption, members for conductinggas to and from said place of absorption, and a pipe coil arrangedsubstantially concentrically insaid annular place and constructed andarranged to form a downward path of flow for absorption liquid on itsexterior surface and interiorly conduct a cooling fluid.

15. An absorption refrigeration system including an absorber formed bytwo upright cylindrical members providing an annular space therebetween,a pipe coil located in said annular space substantially equidistant fromboth said members, a member for conducting absorption liquid to theupper part of saidannular space, members for conducting gas to and fromopposite ends of said annular space, said pipe coil being constructedand arranged to interiorly conduct cooling fluid, a receptacle in theupper part of said annular space and to which liquid is conducted,

and acapillary siphon for distributing liquid from 7 said receptacleonto an upper turn of said pipe coil.

16. In a refrigeration system of the kind in which refrigerant liquidevaporates and diffuses into an inert gas and is thereafter absorbed,the improvement which consists in alternately flowing absorption liquidin free falling condition and in heat exchange relation with a coolingmedium, and flowing a mixture of refrigerant vapor and inert gas on eachside of the descend,-

ing liquid in direct contact therewith in paths of like characteristicand of a width on the order of three sixteenths of an inch.

17. In a refrigeration system. of the kind in which refrigerant liquidevaporates and diffuses into an inert gas and is thereafter absorbed,the

improvement which consists in flowing absorpv tion liquid in asheet-like path in free falling condition, obstructing the free fall ofliquid in said path, flowing a mixture of refrigerant vapor and inertgas on each side of said sheet-like path in direct contact with theabsorption liquid in paths of like characteristic and of awidth on theorder of three sixteenths of an inch, and cooling the obstructingmedium.

18. A cooling element including wall structure forming a horizontallynarrow, vertically elongated space a plurality of conduit sectionslocated one above another centrally in said space and adapted tointeriorly conduct a fluid to be cooled, means for deliveringrefrigerant liquid upon the exterior of said conduit sections, andmembers for conducting gas to and from said space, the horizontal widthof said spacebeing such as to provide a minimum diffusion distancewithout bridging of liquid.

19. A cooling element including a' plurality of inclined conduitsections located one above another so that liquid will flow along theexterior of said sections and drop from one upon another, wall structureforming a closed space around said conduit sections equidistant fromdiametrically opposite sides of the conduit forming said sections, meansfor delivering liquid refrigerant above said conduit sections membersfor conducting gasto the upper part of and from the lower part of saidspace, and connections for flow of fluid to be cooled interiorly of saidconduit sections, the distance of said wall structure from said conduitsections being such as to provide a minimum diffusion distance withoutbridging of liquid.

20. A refrigeration system including structure forming a substantiallyannular place of evaporation, means for conducting liquid refrigerantfluid to said place of evaporation, members for conducting inert gas toand from said place of evaporation, and a member for conducting liquidin contact withthe gas and located centrally in said place ofevaporation, said structure and members being spaced to provide aminimum difiusion distance without bridging of liquid.

21. Refrigeration apparatus of an absorption type including a condenser,an absorber, means for conducting water in cooling relation with saidabsorber, means for causing flow of air in contact with said condenser,and means for flowing water which has been heated by said absorber andconducting the heated water into contact with said condenser, wherebythe water is cooled by evaporation into the air stream to increase itscapacity for cooling the condenser.

22. In the art of producing refrigeration with the aid of a systemhaving an absorber and a ing structure forming a substantially annularplace. of absorption, means for conducting absorption liquid to saidplace of absorption, means for conducting gas .to and from said place ofabsorption, and a member for conducting absorption liquid in contactwith gas and arranged in said place of absorption so that liquid flowssubstantially concentrically in said annular place in contact with twoannular streams of gas.

24. Refrigerating apparatus including a generator for expellingrefrigerant from solution, a condenser connected to receive and adaptedto condense the expelled refrigerant, a principal evaporator connectedto receive the condensed refrigerant from the condenser for primaryevaporation, said evaporator including an outer relatively wide vessel,a pipe coil situated relatively close to the inside wall of said vessel,an inner wall spaced inward of said pipe coil equal to its spacing fromthe outer wall, a liquid holderand spreader above said pipe coil forequalizing distribution of liquid refrigerant thereon, an absorber,means to circulate absorption liquid between the generator and theabsorber, means 'to conduct weak gas from the absorber and introducethe-same into said evaporator, and means to conduct rich gas from theevaporator to the absorber. I

25. Refrigerating apparatus including a generator for expellingrefrigerant from solution, a condenser connected to receive and adaptedto condense the expelled refrigerant, a principal evaporator connectedto receive the condensed refrigerant from the condenser for primaryevaporation, sai'd exaporator including an outer relatively widecylinder, a pipe coil situated relatively close to the inside wall ofsaid cylinder, an inner cylinder spaced inward of said pipe coil equalto its spacing from the outer wall, said inner cylinder having adiameter at least equal to several times the width of the space betweenthe cylinders, a liquid holder and spreader above said pipe coil forequalizing distribution of liquid refrigerant thereon, an absorber,means to circulate absorption liquid between the generator and theabsorber, means to conduct Weak gas from the absorber and introduce thesame into said evaporator, and means to conduct rich gas from theevaporator to the absorber.

2'6. Refrigerating apparatus including a generator for expellingrefrigerant from solution, a condenser connected to receive and adaptedto condense the expelled refrigerant, a principal evaporator connectedto receive the condensed refrigerant from the condenser for primaryevaporation, said evaporator including an outer relatively wide vessel,a pipe coil situated relatively close to the inside wall of said vessel,anenlarged conduit portion forming an inner wall spaced inward of saidpipe coil equal to its spacing from the outer wall, a liquid holder andspreader above said pipe coil for equalizing distribution of liquidrefrigerant thereon, an absorber, means to circulate absorption liquidbetween the generator and the absorber, means to conduct weak gas fromthe absorber to and through said enlarged conduit portion and into saidevaporator, and means to conduct rich gas from the evaporator to theabsorber.

27. Refrigerating apparatus including a generator for expellingrefrigerant from solution, a condenser connected to receive and adaptedto condense the expelled refrigerant, a principal evaporator connectedto receive the condensed refrigerant from the condenser for primaryevaporation, said evaporator including an outer relatively wide vessel,a pipe coil situated relatively close to the inside wall of said vessel,an inner wall spaced inward of said pipe coil equal to its spacing fromthe outer wall, a liquid holder and spreader above said pipe coil forequalizing distribution of liquid refrigerant thereon including a wickhaving a horizontal lower edge, an absorber, means to circulateabsorption liquid between the generator and the absorber, means toconduct weak gas from the absorber and introduce the same into saidevaporator, and means to conduct rich gas from the evaporator to theabsorber;

28. Refrigerating apparatus including a generator for expellingrefrigerant from solution,-a condenser connected to receive and adaptedto condense the expelled refrigerant, a principal evaporator connectedto receive the condensed refrigerant from the condenser for primaryevaporation, said evaporator including an outer relatively wide vessel,a pipe coil situated relatively close to the inside wall of said vessel,an ,inner Wall spaced inwardly of said pipe coil equal to its spacingfrom the outer wall, a liquid holder and spreader above said pipe coilfor equalizing distribution of liquid refrigerant thereon, an absorberincluding an outer relatively wide vessel, a pipe coil situatedrelatively close to the inside wall of said last-mentioned vessel, aninner Wall spaced inwardly of said pipe coil equal to its spacing fromthe outer wall and a liquid holder and spreader above saidlast-mentioned pipe coil, means to circulate absorption liquid betweenthe generator and the absorber, means to conduct weak gas from theabsorber and introduce the same into said evaporator, and means toconduct rich gas from the evaporator to the absorber.

29. Refrigerating apparatus including a gen-- erator for expellingrefrigerant from solution, a

condenser connectedto receive and adapted tocondense the expelledrefrigerant, a principal evaporator connected to receive the condensedrefrigerant from the condenser for primary evaporation, an absorber,said absorber including an outer relatively wide vessel, a pipe coilsituated relatively close to the inside wall of said vessel, an innerwall spaced inwardly of said pipe coil equal to its spacing from theouter Wall, a liquid holder and spreader above said pipe coil forequalizing distribution of liquid refrigerant thereon, means tocirculate absorption liquid between the generator and the absorber,means to conduct weak gas from the absorber and introduce the same intosaid evaporator, and means to conduct rich gas from the evaporator tothe absorber.

30. In refrigerating apparatus of the kind in which refrigerant diffusesinto inert gas, a vessel including means for flow of a first liquidhaving a surface, means to flow a second liquid on said surface, saidfirst means being formed so that said second liquid drips from part topart of said surface, means to circulate inert gas adjacent saidsurface, said vessel including a wall limitingthe path of flow of inertgas adjacent said surface, said surface and wall being spaced to providea minimum diffusion distance without bridging of liquid, said surfaceand wall being mutually irregular to provide turbulence, and membersconnected to said vessel to form a system for circulation of liquid andgas.

31.,In a refrigerating system of the kind employing an inert gas,structure providing a path of flow for inert gas including a wall, aconduit in said path of flow of inert gas connected for flow of liquidtherethrough, means to cause liquid to flow on the exterior of saidconduit, said conduit being formed so that liquid flowing on theexterior thereof drips from part to part of said conduit, said conduitbeing relatively close to said wall to provide a gap therebetween insaid path of flow of inert gas without bridging of such gap by liquidflowing over the exterior of said conduit and dripping from part to partthereof, and a member on the opposite side of said conduit from saidwall and relatively close to said conduit to provide a gap therebetweenin said path of flow of inert gas without bridging of the last-mentionedgap by liquid flowing over said conduit and dripping from part to partthereof.

ALBERT R. THOMAS.

